The present invention relates to a laminated magnetic core for rotating electric machines and a rotating electric machine comprising such laminated magnetic core.
The machine is in the first place intended as a generator in a power station for generating electric power.
The invention is applicable to rotating electric machines such as synchronous machines and normal asynchronous machines. The invention is also applicable to other electric machines such as dual-fed machines and applications in synchronous static current converter cascades, outerpole machines and synchronous flow machines provided their windings are manufactured with insulating electric conductors, and preferably for high voltages. High voltages shall be understood here to mean electric voltages in excess of 10 kV.
Similar machines have conventionally been designed for voltages in the range 15-30 kV, and 30 kV has normally been considered to be an upper limit. This usually means that a generator must be connected to the power network via a transformer which steps up the voltage to the level of the power networkxe2x80x94in the range of approximately 130-400 kV.
A machine which can operate at higher power levels and which can be directly connected to a power network is known from PCT/SE97/00874.
The laminations in laminated stator cores (laminated magnetic cores) for large electric machines are normally laid one by one with overlap in such a way that grooves in the laminations match facing surfaces in the dovetail-shaped wedge of the stator frame. (See FIG. 2.) To enable the lamination to assume its position it is bent sufficiently for the dovetail-shaped groove part to pass the surface of the dovetail-shaped wedge. This method of manufacture is relatively complicated, time-consuming and thus expensive.
The object of the present invention is to solve the problems mentioned above. This is achieved with a laminated magnetic core for rotating electric machines as defined in claim 1, and a rotating electric machine comprising a laminated magnetic core of the type described above as defined in claim 10. The laminated magnetic core according to the present invention comprises a number of stack members, each consisting of a number of sheets of metal joined together. Each stack member is provided with two identical grooves arranged to cooperate with wedge members designed to join the stack members together. Each wedge member has two protrusions arranged symmetrically in relation to the longitudinal axis of the wedge member. Each groove in the stack member has at least one part shaped to fit said protrusion. The stack members in the laminated magnetic core are stacked on and partially overlapping each other to form different layers of stack members, the grooves in the stack members in the various layers being arranged substantially opposite each other. The wedge members are arranged in the grooves with a protrusion abutting the complementary shape of the groove in such a manner that the stack members in one layer are secured counter-clockwise in tangential direction and that the stack members in at least one of the adjacent layers are secured clockwise in tangential direction. The laminated magnetic core also includes locking members arranged at least at the transition between layers secured clockwise and layers secured counter-clockwise in order to prevent tangential movement between the different layers.
The above-mentioned laminated magnetic core according to the present invention is easy and quick to manufacture. It is thus also relatively inexpensive to manufacture.